brain of mat kelcey...

tokenising the visible english text of common crawl

December 10, 2011 at 04:00 PM | categories: Uncategorized

Common crawl is a publically available 30TB web crawl taken between September 2009 and September 2010. As a small project I decided to extract and tokenised the visible text of the web pages in this dataset. All...

finding phrases with mutual information

November 15, 2011 at 11:00 PM | categories: Uncategorized

continuing on with my series of mutual information experiments how might we extend the technique to identity sequences longer than just two terms?one novel way is to identify the bigrams of interest, replace them with a single...

collocations in wikipedia, part 2

November 05, 2011 at 05:00 PM | categories: Uncategorized

in my last post we went through mutual information as a way of finding collocations.the astute reader may have noticed that for the list of top bigrams i only showed ones that had a frequency above 5,000.why this...

collocations in wikipedia, part 1

October 19, 2011 at 08:00 PM | categories: Uncategorized

collocations are combinations of terms that occur together more frequently than you'd expect by chance. they can include proper noun phrases like 'Darth Vader' stock/colloquial phrases like 'flora...

an exercise in handling mislabelled training data

October 03, 2011 at 08:00 PM | categories: Uncategorized

as part of my diy twitter client project i've been using the twitter sample streams as a source of unlabelled data for some mutual information analysis. these streams are a great source...

do all first links on wikipedia lead to philosophy?

August 13, 2011 at 03:00 PM | categories: projects

using hadoop and a wikipedia dump to test the hypothesis that all first links on pages eventually lead to philosophy.

dimensionality reduction using random projections.

May 10, 2011 at 08:31 PM | categories: Uncategorized

previously i've discussed dimensionality reduction using SVD and PCA but another interesting technique is using a random projection.in a random projection we project A (a NxM matrix) to A' (a NxO, O < M) by the transform AP=A' where P...

pseudocounts and the good-turing estimation (part1)

April 03, 2011 at 03:04 PM | categories: Uncategorized

say we are running the bar at a soldout bad religion concert. the bar serves beer, scotch and water and we decide to record orders over the night so that we can know how much to order for tomorrow's gig...drink#salesbeer1000scotch300water200using...

visualising the consistent hash

September 26, 2010 at 04:00 PM | categories: Uncategorized

consider the problem of allocating N resources across M servers (N >> M)a common approach is the straight forward modulo hash...if we have 4 servers; servers = [server0, server1, server2, server3] we can allocate a resource to a server...

simple text search in ruby using ferret

September 12, 2010 at 09:28 PM | categories: Uncategorized

ferret is a lightweight text search engine for ruby, a bit like lucene but with less (ie no) java.i've been looking at it today as part of my named entity extraction prototype which needs to be able to fuzzily match...

my list of cool machine learning books

August 06, 2010 at 06:35 PM | categories: Uncategorized

for the last month or so i've had my head down and have been focusing more on theory (ie reading) than on practice (ie coding)so rather than write no blog post here's mats-list-of-cool-machine-learning-books in the order i think you should...

brutally short intro to weka

July 03, 2010 at 05:35 PM | categories: Uncategorized

weka is a java based machine learning workbench that i've found useful to playing with to help understand some standard machine learning algorithms. in this quick demo i show how to build a classifier for three simple datasets; two of...

friend clustering by term usage

June 25, 2010 at 11:39 PM | categories: Uncategorized

recently signed up to the infochimps api and wanted to do something quick and dirty to get a feel for it.so here's a little experiment get the people i follow on twitterlook up the words that "represent" them...

country codes in world cup tweets - viz1

June 21, 2010 at 07:43 PM | categories: Uncategorized

#worldcup tweet viz1 from Mat Kelcey on Vimeo.here's a simple visualisation of the use of official country codes (eg #aus) in a week's worth of tweets from the search stream for #worldcup.rate is about 2hours of tweets per sec. orb...

moving average of a time series in R

June 15, 2010 at 04:15 PM | categories: Uncategorized

in this a sliding window of 3 elements123456789> x = c(3,1,4,1,5,9,2,6,5,3,5,8)> ra_x = filter(x, rep(1,3)/3)> ra_xTime Series:Start = 1 End = 12 Frequency = 1 [1] NA 2.666667 2.000000 3.333333 5.000000 5.333333 5.666667...

#worldcup twitter analytics

June 14, 2010 at 10:06 PM | categories: Uncategorized

since the world cup started i've spent more time looking at twitter data about the games than the actual games themselves. what a sad data nerd i am!anyways, here's the first few days analysis based the use of official country...

a quick study in tf/icf

June 09, 2010 at 09:58 PM | categories: Uncategorized

while doing some more research on trending algorithms i came across a cool little paper about term frequency normalisation for streaming data: TF-ICF: A New Term Weighting Scheme for Clustering Dynamic Data Streams.i'm finding streaming related algorithms quite interesting lately...

5 minute ggobi demo

June 04, 2010 at 11:12 PM | categories: Uncategorized

brutally short demo of ggobi from Mat Kelcey on Vimeo.note: non embedded version has higher res at full screen...

how many terms in a trend?

May 11, 2010 at 07:46 PM | categories: Uncategorized

i've been poking around with a simple trending algorithm over the last few weeks and have uncovered a problem that, like most interesting ones, i'm not sure how to solve. the question revolves around discovering multi terms trends. a sensible...

trending topics in tweets about cheese; part2

May 01, 2010 at 04:54 PM | categories: Uncategorized

prototyping in ruby was a great way to prove the concept but my main motivation for this project was to play some more with pig.the main approach will be maintain a relation with one record per...

trending topics in tweets about cheese; part1

April 27, 2010 at 11:42 PM | categories: Uncategorized

what does it mean for a topic to be 'trending'? consider the following time series (430e3 tweets containing cheese collected over a month period bucketed into hourly timeslots)without a formal definition we can just look at this and...

latent semantic analysis via the singular value decomposition (for dummies)

April 19, 2010 at 08:50 PM | categories: Uncategorized

i've been trying to get a deeper understanding of latent semantic analysis for awhile now. last week i came to the conclusion the other way to truly understand would be to start from the ground up ...

cool bash stuff; mkfifo

April 15, 2010 at 09:33 PM | categories: Uncategorized

mkfifo is one of those shell commands provided as part of coreutils that not many people seem to know about.here's an (semi contrived) example close to something i did the other day to show how awesome it issay you have...

e10.6 community detection for my twitter network

April 04, 2010 at 12:58 PM | categories: Uncategorized

last night i applied my network decomposition algorithm to a graph of some of the people near me in twitter.first i build a friend graph for 100 people 'around' me (taken from a crawl i did last year). by 'friend'...

e10.5 revisiting community detection

March 30, 2010 at 08:42 PM | categories: Uncategorized

i've decided to switch back to some previous work i did on community detection in (social) graphsthe last chunk of code i wrote which tried to deal with weighted directed graphs was terribly, terribly, broken but it seems that simplifying...

brutally short intro to collaborative filtering

March 18, 2010 at 08:38 PM | categories: Uncategorized

my favourite recommendations system is the collaborative filter; it gives good results and is easy to understand and extend as required.it works on the intuition that if i like coffee, chocolate and ice cream ...

sentiment analysis training data using mechanical turk

March 12, 2010 at 09:57 PM | categories: Uncategorized

want to try doing some sentiment analysis work on tweets but i need some good training data.i could label a heap of tweets myself as being positive, neutral or negative but instead this seems to be the perfect job for...

mongodb + twitter + yahoo term extractor = fun!

March 07, 2010 at 09:38 PM | categories: Uncategorized

ran a little experiment in using yahoo term extraction yesterday and it worked well enough. here's some code to pass some text to yahoo and get back an array of termsi've got to say mongodb is such an easy tool...

what to do with a week off?

February 22, 2010 at 06:42 PM | categories: Uncategorized

this week i'm between jobs so i have (a little) more time than usual to hack.i've got a list of pending things to do but can't decide what to do next, here's my list in (sort of) priority order... ...

semi supervised naive bayes for text classification

February 14, 2010 at 09:46 PM | categories: Uncategorized

experiment 13; a test of semi supervised naive bayes for text classification is complete.semi supervised algorithms seem to work pretty well and i can see how they are a huge benefit for text classification where you can have an enormous...

e12.3 stat syns FAIL!

February 05, 2010 at 08:31 PM | categories: Uncategorized

after quite a bit of hacking the statistical synonyms idea doesn't seem to give terribly interesting results so i'm going onto do something else.for the record here's what I did do though.... generate 3grams from 800e3 tweetscollect n-grams...

an intro to semi supervised document classification

January 31, 2010 at 02:02 PM | categories: Uncategorized

here's a great lecture from tom mitchell about document classification using a semi supervised version of naive bayes.semi supervised algorithms only require some of the training examples to be labeled and are able to make use of any unlabelled ones,...

e12.2 entity set expansion

January 28, 2010 at 08:18 PM | categories: Uncategorized

i've been doing some reading for my statistical synonyms project and have uncovered a heap of cool papers. most of them are around an idea (from the 1950's!) called the distributional hypothesis that simply states that words that appear in...

e12.1 statistical synonyms

January 23, 2010 at 12:54 PM | categories: Uncategorized

i've had an idea brewing in my head for awhile now seeded by a great talk by peter norvig about statistically approaches to find patterns in data.one thing he alludes to is the generation of synoyms based on n-gram models.the...

a pig screencast

January 17, 2010 at 02:22 PM | categories: Uncategorized

pig demo from Mat Kelcey on Vimeo.based on a talk i gave at work recently...

tweets about cheese

November 15, 2009 at 08:45 PM | categories: Uncategorized

people tweet about all sorts of stuff.sometimes it's really important ground breaking world changing stuff... but most of the time it's ridiculous waste of time stuff like 'i ate some cheese'in fact how much do people actually tweet...

xargs parallel execution

November 06, 2009 at 09:57 PM | categories: Uncategorized

just recently discovered xargs has a parallelise option!i have 20 files, sample.01.gz to sample.20.gz, each ~100mb in size that i need to run a script overone option is zcat sample*gz | ./script.rb > output but this...

e11.3 at what time does the world tweet?

October 28, 2009 at 09:22 PM | categories: Uncategorized

consider the graph below which shows the proportion of tweets per 10 min slot of the day (GMT0)it compares 4.7e6 tweets with any location vs  320e3 tweets with identifiable lat lons some interesting observations with unanswered questions... ...

e11.2 aggregating tweets by time of day

October 24, 2009 at 01:02 PM | categories: Uncategorized

for v3 lets aggregate by time of the day, should make for an interesting animationbrowsing the data there are lots of other lat longs in data, not just iPhone: and ÜT: there are also one tagged with Coppó:, Pre:, etc...

e11.1 from bash scripts to hadoop

October 18, 2009 at 02:10 PM | categories: Uncategorized

let's rewrite v1 using hadoop tooling, code is on githubwe'll run hadoop in non distributed standalone mode. in this mode everything runs in a single jvm so it's nice and simple to dev against.in v1 it wasbzcat sample.bz2 | ./extract_locations.pl...

e11.0 tweets around the world

October 16, 2009 at 08:47 PM | categories: Uncategorized

was discussing the streaming twitter api with steve and though i knew about the private firehose i didn't know there was a lighter weight public gardenhose interface!since discovering this my pvr has basically been running curl -u mat_kelcey:XXX...

e10.4 communities in social graphs

October 06, 2009 at 08:05 PM | categories: Uncategorized

social graphs, like twitter or facebook, often follow the pattern of having clusters of highly connected components with an occasional edge joining these clusters.these connecting edges define the boundaries of communities in the social network and can be identified by...

simple statistics with R

October 03, 2009 at 03:43 PM | categories: Uncategorized

i'm learning a new statistics language called R and it's pretty cool.make a vector ...12> c(3,1,4,1,5,9,2,6,5,3,5,8) [1] 3 1 4 1 5 9 2 6 5 3 5 8turn it into a frequency table ...123> table(c(3,1,4,1,5,9,2,6,5,3,5,8))1 2 3 4 5...

do a degree via youtube

October 01, 2009 at 08:40 PM | categories: Uncategorized

i'm amazed by how much great content is on youtube, how could you NOT learn something!?13 x 1hr Statistical Aspects of Data Mining (Stats 202)20 x 1hr Machine Learning...

e10.3 twitter crawl progress

September 29, 2009 at 08:43 PM | categories: Uncategorized

since the twitter api is rate limited it's quite slow to crawl twitter and after a most of a week i've still only managed to get info on 8,000 users. i probably should subscribe to get a 20,000 an hr...

e10.2 tgraph crawl order example

September 21, 2009 at 09:58 PM | categories: Uncategorized

let's consider an example of the crawl order for tgraph...we seed our frontier with 'a' and bootstrap cost of 0.fetching the info for 'a' shows 2 outedges to 'b' and 'c', from our cost formula these all have cost 0...

e10.1 crawling twitter

September 19, 2009 at 09:31 PM | categories: Uncategorized

our first goal is to get some data and the twitter api makes getting the data trivial. i'm focused mainly on the friends stuff but because it only gives user ids i'll also get the user info so i can...

e10.0 introducing tgraph

September 19, 2009 at 02:41 PM | categories: Uncategorized

so e9 sip is on hold for a bit while i kick off e10 tgraph. was looking for another problem to try hadoop with and came across a classic graph one, pagerank. a well understood algorithm like page rank will...

first hadoop experiment

September 16, 2009 at 07:26 PM | categories: Uncategorized

just finished my first hadoop experiment.matpalm.com/sipnot fantastic results but heaps of of feedback from hadoop mailing groupmore results coming soon...

how using compressed data can make you app faster

June 28, 2009 at 11:32 AM | categories: Uncategorized

when working with larger data sets (ie more than can fit in memory) there are two important resources to juggle… cpu. how quickly can you process the data. disk io. how...
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wikipedia philosophy : do all first links on wikipedia lead to philosophy? (aug 2011)

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the co-evolution of cooperative behaviour (1997) evolving neural nets with genetic algorithms for communication problems.

old projects...